Skylights provide for the transmission of natural light to the interior of buildings. Popular both in commercial and residential structures, skylights provide a more pleasing and desirable source of interior illumination and reduce the consumption of electricity.
Traditional skylights are constructed with a light shaft between a skylight lens upon a building roof and an opening in an interior ceiling. The light shaft may include conventional framing and sheetrocking between the skylight lens and the interior opening below.
Alternatively, tubular skylights may be used. A tubular skylight may include an exterior dome upon the roof of the building, an interior light diffuser at the interior building ceiling, and a light tube disposed between the dome and diffuser.
Tubular skylights include a number of unique characteristics that may be advantageous in certain applications. For examples, tubular skylights may be purchased as pre-assembled systems, making installation easier and requiring less construction expertise. Tubular skylights also may be used without the need for reinforcing structural supports. Tubular skylights may require less involved constructional logistics that the afore-mentioned light shaft skylights. They may also be used in spaces too small for such traditional skylights.
Additionally, tubular skylights may be installed in less time than is required to install a traditional skylight. Installation of currently-existing tubular skylights may include the following steps. First, the preferred location of the interior diffuser may be located upon the interior building ceiling, then perhaps adjusted so as to avoid interference with existing ceiling joists. Thereafter, from the attic space above the ceiling, a direct path may be established between the ceiling location to the exterior building roof. Such a direct path may be desirable, to avoid elbow joints with the use of rigid skylight tubes or bends with the use of flexible skylight tubes, so as to provide a straight path for incoming sunlight, inasmuch as a straight path results in greater transmission of such sunlight. However, such a direct path may not be available, either because of framing, HVAC ductwork, piping, and/or wiring within the attic space, or because of interfering structures upon the roof. Once final ceiling and roof locations have been identified, holes are cut through each. Thereafter, various configurations of interior ceiling diffuser mounts and rooftop structural mounts may be utilized, as commercially available. Next, a light tube is disposed between the roof and the ceiling. However, unless a direct line could be established between the roof and the ceiling, either a flexible light tube (itself bent) or a rigid light tube with one or more elbow units may need to be used between the two openings to connect the ceiling diffuser to the rooftop mount.
Experience with the currently-existing tubular skylights has identified several challenges. For example, dimensions between the exterior roof and the interior ceilings vary greatly from one building to another. As noted above, for example, placement of the interior diffuser within a building depends not only upon the particular dimensions of the individual building, which may differ significantly from one application to another, but also upon the subjective preferences of the individual installer or building owner. Furthermore, as to such a structure, depending upon placement of the exterior dome upon the roof relative to placement of the diffuser on the interior ceiling, still further dimensional variables are presented. For example, different roofs have different pitches, and different rooftop structures, such as vents, chimneys, and the like, might be found upon any particular building during any particular application that would require placement of the rooftop unit in a different location.
Simply put, the variables to be reckoned with for proper installation of a tubular skylight within a particular building include the location of the interior diffuser, the location of the exterior roof unit relative to the interior diffuser, and the angle between those two components. Economy of manufacture urges that standardization of tubular skylight components would be desirable, yet a single configuration of the currently-known tubular skylights does not account for the virtually infinite variations of such variables encountered in the field. It would be desirable to have a skylight system with a tubular tunnel assembly that could be finely adjusted to meet the variations in angle between the rooftop assembly and the interior assembly.
The apparatus of U.S. Pat. No. 5,596,848 purports to be adapted to suit a variety of roof pitches in a tubular skylight assembly. However, use of that apparatus is limited by its inherent features. While some adjustment of the angular orientation of the described apparatus might be made about lugs, the sides 23 of the apparatus constrain such movement in many directions. Furthermore, the apparatus admits only to articulation about fixed horizontal axis 26. While axis 26 may be changed at installation between various pairs of the grooves formed on the rim of the base, that number of pairs of grooves is finite, and therefore the adjustability of the angular orientation of the depending light tube likewise is finite. The described apparatus also is comparatively complicated to manufacture and, should a lug be broken, the apparatus would be rendered useless.
It has also been found preferable to minimize the use of elbows within the light tube. While the currently known tubular skylight systems may require the use of such elbows to provide for connection between the rooftop unit and the interior diffuser, use of such elbows has been found to reduce the amount of light transmitted through the skylight assembly. Examples of such elbows are shown in U.S. Pat. No. 6,256,947. It would be preferable to avoid the use of any such elbows.
Even with the use of flexible tubing between the rooftop assembly and the interior diffuser, experience has shown that it may be preferable in some applications for such flexible tubing to extend directly, in a straight line, from the rooftop mount to the interior diffuser, rather than to bend or to use rigid elbows so as to adapt for angular displacements between the rooftop mount and the interior diffuser. As noted above, every elbow or bend in the light tube may result in diminishment of the amount of sunlight transmitted by the skylight system.
As suggested above, the buildings in which tubular skylights might be installed often have pitched roofs. While roof pitch usually is at one of only several standard gradients, the angle at which the light tunnel beneath such a roof must traverse, relative to the plane of the roof, to reach the interior diffuser panel may vary infinitely between different applications. Experience in the field teaches that precise measurement, satisfactory alignment, and efficient light transmission can be difficult to achieve with some presently-known tubular skylights. Careful measurement and advance planning, even by a skilled craftsman, must account for satisfactory final installation in three dimensions, which multiplies the opportunity for human error. It would be desirable therefore to have a skylight assembly that would allow for simple yet effective fine tuning in the field of the angular orientation of the light tunnel between the roof mount and the interior diffuser.
It has also come to be recognized that some tradesmen installing tubular skylights prefer to assemble and install as much of the skylight system as possible from the building roof, minimizing the amount of time and assembly required indoors, either inside the building itself or in the attic space between the ceiling and roof. Because those who install tubular skylights view as preferable those devices that can be more completely assembled and installed from the rooftop, it would be desirable to have a skylight system that allows for assembly and installation of as much of the system as possible from the exterior building roof.
Still further, differential thermal expansion between various components of a tubular skylight assembly must be recognized. Variations in the temperatures between a building interior and exterior, as well as variations in ambient outdoor temperature between the yearly seasons, may cause differential thermal expansion between the components of some presently-known tubular skylight systems that impairs the integrity of the skylight system. It would therefore be desirable to have a tubular skylight system that addresses differential thermal expansion concerns and thereby preserves the integrity of the tubular skylight system.
Furthermore, it has been found in some installations that humidity intrudes to the interior of a tubular skylight system, and may condense at the exterior skylight dome. It would be preferable, therefore, to have a tubular skylight system that allows for drainage of condensed moisture from the skylight dome to the exterior of the building roof.
It would thus be desirable to have a tubular skylight system meeting one or more of the foregoing concerns that is also durable, reliable, and easily and inexpensively manufactured.
While various tubular skylights have been developed, no design has emerged that generally encompasses all of the desired characteristics as hereafter presented in accordance with the subject technology.